1. Field of the Invention
The present invention relates to image sensors.
2. Description of Related Art
Typical image sensors, such as those used in color copiers are one-dimensional and have either a 3-line CCD unit or a 4-line CCD unit. A typical 3-line CCD unit has three photodiode arrays—one for each of the three primary colors R, G and B. A typical 4-line CCD unit has, in addition to the RGB photodiode arrays, a monochrome (B/W) photodiode arrays.
Many image reading devices, such as color copiers, include a color mode and a monochrome mode. In the color mode, a color image is read. In the monochrome mode, a monochrome image is read. The typical 3-line CCD unit extracts a monochrome signal from the signals from the RGB photodiode arrays. The typical 4-line CCD unit obtains a monochrome signal from the B/W photodiode arrays.